Physical Digestion
Overview
Before any enzyme can work on your food, the food has to be broken into small pieces. That mechanical breaking up, by teeth, by the churning stomach and by bile splitting fat into droplets, is physical digestion. It changes the size of the food, not its chemistry, and it sets the stage for the chemical digestion that follows.
In this lesson you will see why chewing matters so much, learn the four kinds of human teeth and the layers inside a tooth, and discover how the stomach and bile each increase the surface area of food. The thread running through it all is one powerful idea: more surface area means faster enzyme action.
Objectives
- Describe physical digestion as the breakdown of food into smaller pieces without chemical change to the food molecules
- State that physical digestion increases the surface area of food for the action of enzymes in chemical digestion
- Identify in diagrams and images the types of human teeth: incisors, canines, premolars and molars
- Describe the structure of human teeth, limited to: enamel, dentine, pulp, nerves, blood vessels and cement, and understand that teeth are embedded in bone and the gums
- Describe the functions of the types of human teeth in physical digestion of food
- Describe the function of the stomach in physical digestion
- [Supplement] Outline the role of bile in emulsifying fats and oils to increase the surface area for chemical digestion
Audio Lesson
Listen to this lesson in the app
Mind map
This topic is mapped out so you can see how the ideas connect.
Open the mind map in the app
Flashcards
Quick recall practice on the facts this topic is tested on.
Practise these cards in the app
Lesson Note
Complete Note Available on the Green Bridge App
Get the Green Bridge CBT app on your phone or computer for the complete IGCSE library: past papers, mark schemes, mind maps, flashcards and audio lessons.
Lesson Evaluation
Congratulations on completing the lesson on Physical Digestion. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Physical digestion is best described as breaking food into smaller pieces: A. by enzymes B. with a chemical change to the molecules C. without a chemical change to the molecules D. into amino acids Answer: C
- A person bites a chunk out of an apple using the flat, chisel-edged teeth at the very front of the mouth. What is the name of these teeth? A. canines B. incisors C. premolars D. molars Answer: B
- The very hard outer layer of the crown of a tooth is the: A. dentine B. enamel C. pulp D. cement Answer: B
- Which part of a tooth contains the nerves and blood vessels? A. enamel B. cement C. pulp D. dentine Answer: C
- The main importance of physical digestion is that it: A. changes food molecules chemically B. increases the surface area of food for enzymes C. absorbs nutrients D. kills bacteria Answer: B
Work through these questions in the app
Work through these questions in the app
Recommended Books
Practice Mock Questions
Want to practice mock questions on Physical Digestion? Download the Green Bridge CBT app to access mock questions and full practice assessments for this topic.
Download The App On Google Playstore
Everything you need to excel in your exams
